SPID#: 5 The primary objective of this research is to characterize the temporal changes (if any) in the cytokine profile of lymph node cells of rhesus macaques experimentally infected with SIVmac251. Several studies have previously shown a high degree of correlation between a shift from a prototype TH1 cytokine profile (based on the coordinated expression of sets of distinct but overlapping cytokines synthesized by lymphoid cells) with progression from infection to disease in both human HIV-1 infection and experimental SIV infection. Our purpose has been and continues to be to systematically characterize such changes (if any). Our laboratory has cloned and sequenced nonhuman primate IL-1a, IL-1b, IL-2, IL-3, IL-4, IL-6, IL-8. IL-10, IL-12a, IL-12b, IL-13, IL-14, IL-15, IL-16, TNF-a, TNF-b, IFN-a, IFN-g, etc.. In addition, our laboratory has prepared recombinant rhesus macaque IL-2, IL-4, IL-12, IL-15 and IFN-g. We have also established a semi-quantitative RT-PCR assay to quantitate each cytokine in mRNA. A set of 6 rhesus macaques have been immunized with influenza, tetanus toxoid, KLH and subsequently infected with SIVmac251. Ex vivo PBMC samples and antigen specific PBMC cultures have been collected at varying intervals prior to and post SIV infection. These samples are currently being analyzed for cytokine profile at the mRNA and protein levels.